To study the possibility of cross-species transmission of CWD, two species of nonhuman primates, squirrel monkeys and cynomologus macaques, were infected orally or intracerebrally with brain material derived from CWD affected deer or elk. Three years after infection four intracerebrally infected squirrel monkeys developed clinical neurological signs and were confirmed by biochemical and pathological testing of brain to have a prion disease. One orally infected squirrel monkey also developed disease. So far no cynomologus macaques have developed any signs of disease. Observations on the remaining monkeys will continue for at least a few more years.